Metal-insulator transition in epitaxial V1−xWxO2(≤x≤0.33) thin films

Abstract

We have fabricated epitaxial ${\text{V}}_{1-x}{\text{W}}_x{\text{O}}_2\left(0\le x\le 0.33\right)$ thin films on ${\text{TiO}}_2$ (001) substrates. The metal-insulator transition temperature of ${\text{VO}}_2$ is systematically reduced by W doping, and eventually a metallic ground state is realized at $0.08\le x\le 0.09$ . Tiny resistivity upturn around 50 K observed for these films suggests an electronic phase separation between a majority metallic matrix and minority insulating puddles. With further increasing $x$ above 0.095, another insulating phase appears while increasing the metal-insulator transition temperature. The elucidated phase diagram gives basic knowledge for devices based on Mott transition.